Describe the Bug:1- Sludge Strider both abilities don't require they are free.2- Sludge Strider leave the battlefield ability triggers even if it leaves itself from battlefield.3- Also if an artifact with toughness 0 enters the battlefield Sludge Strider triggers only once.Which card did behave improperly?Sludge Strider

What exactly should be the correct behavior/interaction?1- Sludge Strider both abilities require if you choose to use the triggers.2- Sludge Strider leave the battlefield ability triggers only if another artifact leaves the battlefield.Pay attention though if it leaves the battlefield or enters the battlefield with another artifact the ability should trigger for the other artifact.3- See 2nd ruling below.Rulings:1- 2/1/2009 If Sludge Strider and another artifact enter the battlefield under your control at the same time, Sludge Strider’s triggered ability will trigger. Similarly, if Sludge Strider and another artifact you control leave the battlefield at the same time, Sludge Strider’s triggered ability will trigger.2- 2/1/2009 If an artifact creature with 0 toughness enters the battlefield under your control, Sludge Strider’s ability will trigger a total of twice: Once when that creature enters the battlefield, and once when it’s put into a graveyard. Both abilities will be put on the stack after the state-based action check that puts the 0-toughness creature into the graveyard is finished.